1. Field of Invention
This invention relates to a device for the mapping of cardiac arrhythmia foci. In particular, it relates to a catheter which is useful for the mapping of cardiac arrhythmia foci containing a grouping of small, non-ring shaped, point electrodes preferably formed in a diamond-shaped configuration, which when activated, produce a pair of bipoles on the catheter.
2. Prior Art
Catheters have been in use for medical procedures for many years. For example, one use is to convey an electrical stimulus to a selected location within the human body. Another use is to assist in monitoring and measuring electrophysiological activity for diagnostic tests within the human body. Thus, catheters may assist in examination, diagnosis and treatment within a human body while positioned at a specific location, which is otherwise inaccessible without more invasive procedures. In use, catheters are inserted into a vein or artery which is near the body surface. These catheters are then guided to a specific location for examination, diagnosis or treatment by manipulating the catheter through the artery or vein of the human body.
Catheters have become increasingly useful in remote and difficult to reach locations within the body. Catheters are used increasingly for medical procedures involving the human heart. In these procedures a catheter is typically advanced to the heart through veins or arteries and then is positioned at a specified location within the heart. Typically, the catheter is inserted in an artery or vein in the leg, neck, upper chest or arm of the patient and threaded, often with the aid of a guidewire or introducer, through various arteries or veins until the tip of the catheter reaches the desired location in the heart.
Cardiac arrhythmia may be transient or persistent. While most arrhythmia occur in individuals having other forms of underlying heart disease, some arrhythmia occur independently. While atrial arrhythmia do not directly cause death as frequently as ventricular arrhythmia, they increase the risk factor for a number of other diseases such as strokes, thrombosis, atherosclerosis, systemic and cerebral embolism and cause a number of additional medical problems. Atrial fibrillation is the most common sustained heart arrhythmia. It is estimated to occur in upwards of 0.4 percent of the adult population and perhaps as many as 10 percent of the population who are 60 years or older.
Certain patients with symptomatic or life threatening cardiac arrhythmia cannot be adequately treated by drugs or common medical devices, such as defibrillation, or by cardioversion. Other forms of treatment are then mandated, which may include surgery.
Another procedure used for treatment of certain types of cardiac arrhythmia within the last 10 to 15 years is catheter ablation. This procedure has been used to interrupt or modify existing conduction pathways associated with arrhythmias within the heart. The particular area for ablation depends on the type of underlying arrhythmia. One common ablation procedure treats atrioventricular (AV) nodal reentrant tachycardia. With this problem ablation of the fast or slow AV nodal pathways has become an accepted treatment. The use of ablation catheters for ablating locations within the heart has been disclosed, for example in U.S. Pat. Nos. 4,641,649, 5,263,493, 5,231,995, 5,228,442 and 5,281,217.
In addition, catheter ablation for the treatment of ectopic atrial tachycardia is disclosed, for example, in Walsh, Edward P. xe2x80x9cAblation of Ectopic Atrial Tachycardia in Childrenxe2x80x9d Radio Frequency Catheter Ablation of Cardiac Arrhythmias, Chap. 23 (1994). See also Tracey, C. N. xe2x80x9cRadio Frequency Catheter Ablation of Ectopic Atrial Tachycardia Using Paced Activation Sequence Mappingxe2x80x9d J. Am. Coll. Cardial. Vol 21, pp. 910-917 (1993).
The sources of energy used for catheter ablation vary. Initially, high voltage, direct current (D.C.) ablation techniques were commonly used. However, because of problems associated with the use of D.C. current, radio frequency (RF) ablation has become a preferred source of energy for the ablation procedures. Other energy sources also considered for ablation of heart tissue include laser, ultrasound, microwave and fulgutronization.
Ablation of a precise location within the heart, such as a focus of a cardiac arrhythmia, requires the precise placement of the ablation catheter within the heart. Precisely positioning the ablation catheter is especially difficult because of the physiology of the heart, particularly as the ablation procedures generally occur while the heart is beating. Commonly, the placement of the catheter is determined by a combination of electrophysiological guidance and fluoroscopy (placement of the catheter in relation to known features of the heart which are marked by radiopaque diagnostic catheters which are placed in or at known anatomical structures such as the coronary sinus, high right atrium and the right ventricle).
Accordingly, the treatment of cardiac arrhythmia has increasingly been dependent upon the ability to identify the precise location or origin in the heart of the abnormal rhythm. The prior art practice for locating an abnormal rhythm is to place a catheter within the heart carrying a standard array of ring and/or tip electrodes. Direct contact of the tip electrode with the cardiac tissue is used for making an intracardiac electrogram in a manner similar to that has been practiced for many years with respect to pacemaker sensing. See, for example, U.S. Pat. Nos. 5,156,151 and 4,365,639.
A relatively new process for sensing arrhythmia within a heart utilizes one or more pairs of circumferential, orthogonal sensing electrodes, such as are disclosed in U.S. Pat. No. 4,365,639. See also Canadian Patent No. 1,192,263. A series of circumferential orthogonal electrodes located in pairs around the body of a catheter are disclosed in U.S. Pat. Nos. 5,385,146, 5,450,846 and 5,579,764. These patents disclose a process whereby a pair or a series of pairs of circumferential orthogonal electrodes are used in conjunction with an ablation or pacing catheter simultaneously to sense electrophysiological activity in the heart and to pace or ablate predetermined locations in the heart. Only localized cardiac signals at precise locations within the cardiac tissue of the heart immediately adjacent to the predetermined location where the orthogonal electrodes are positioned are sensed by the orthogonal electrode pairs. The specific design and arrangement of these orthogonal electrode pairs limits their use within the heart to simultaneous sensing and pacing or ablating activities. While the procedures disclosed by these patents are quite useful once the focus of the cardiac arrhythmia has been determined, it is necessary to first identify the general location of the arrhythmia focus within the cardiac tissue.
Accordingly, it is an object of the invention to disclose a product for the mapping of cardiac tissue to disclose the location of cardiac arrhythmia foci.
It is a further object of the invention to disclose a catheter containing a plurality of point electrodes which form a pair of bipoles for the sensing of the direction of an activation wave generated by cardiac arrhythmia foci as the wave passes the pair of bipoles.
It is a still further object of the invention to disclose a catheter for the sensing of the direction of an activation wave generated by cardiac arrhythmia foci in the heart as the wave passes a pair of bipoles secured to the catheter, wherein the bipoles are formed from two pair of point electrodes formed in a diamond-shaped configuration, wherein the two pair of point electrodes are secured to the surface of the catheter within an arc of no more than 180xc2x0 around the circumference of the catheter when viewed from the distal end of the catheter such that the point electrodes may be in constant contact with the surface of the cardiac tissue.
It is a still further object of the invention to disclose a catheter containing a plurality of point electrodes formed in a pattern which is capable of sensing an activation wave from an ectopic atrial tachycardia and other forms of cardiac arrhythmia foci within the heart.
It is a still further object of the invention to disclose a process for the mapping of cardiac arrhythmia foci in a heart by use of a catheter containing a plurality of point electrodes forming at least two bipoles, wherein the bipoles are preferably about 90 degrees apart from each other.
These and other objects can be obtained by the disclosed process for the treatment of cardiac arrhythmia focus and design of a catheter containing a pair of bipoles for use for that process which are disclosed by the instant invention.
The present invention is a catheter for sensing electrophysiological activity within a human heart comprising:
an elongated catheter body having a distal end,
a first and second point electrodes which are secured to the elongated catheter body comprising a first bipolar pair of electrodes, and
third and fourth point electrodes which are secured to the catheter body comprising a second bipolar pair of electrodes, wherein a line passing between the third and fourth point electrodes is within about 45 degrees of being perpendicular to a line passing through the first and second point electrodes and wherein all four point electrodes are located within the surface of the catheter forming no more than half of the circumference of the catheter when viewed from its distal end such that all four point electrodes can be in simultaneous contact with the surface of the heart during the sensing procedure.
Preferably, these four point electrodes are formed in a diamond-shaped configuration.
The present invention also includes a catheter for sensing electrophysiological activity within a human heart comprising
an elongated catheter body having a distal end,
a first and second point electrode which are secured to the elongated catheter body, comprising a first bipolar pair of electrodes,
third and fourth point electrodes which are secured to the catheter body comprising a second bipolar pair of electrodes, wherein a line passing between the third and fourth point electrodes is within about 45 degrees of being perpendicular to a line passing through the first and second point electrodes, and wherein all four point electrodes are located within the surface of the catheter forming no more than half of the circumference of the catheter when viewed from its distal end, such that all four point electrodes are capable of simultaneous contact with the surface of the heart during the sensing procedure, and
a unipolar electrode secured to the distal end of the catheter body.
Preferably, these four point electrodes are formed in a diamond-shaped configuration.
The present invention also includes a catheter for sensing electrophysiological activity within a human heart comprising
an elongated catheter body having a distal end,
a first and second point electrode which are secured to the elongated catheter body, comprising a first bipolar pair of electrodes, and
a third point electrode which is secured to the catheter body which operates with the second point electrode to form a second bipolar pair of electrodes, wherein a line passing between the first and second point electrodes is generally perpendicular to a line passing between the second and third point electrodes and wherein all three point electrodes are located within the surface of the catheter forming no more than half of the circumference of the catheter when viewed from its distal end, such that all three point electrodes are capable of simultaneous contact with the surface of the heart during the sensing activity.
The present invention also includes a process for the mapping of cardiac arrhythmia focus activity within a heart comprising
introducing a catheter within a chamber of the heart, wherein the catheter comprises an elongated catheter body having a distal end, first and second point electrodes which are secured to the elongated catheter body and which comprise a first bipolar pair of electrodes, and third and fourth point electrodes which are secured to the catheter body comprising a second bipolar pair of electrodes, wherein a line passing between the third and fourth point electrodes is within about 45 degrees of being perpendicular to a line passing through the first and second point electrodes and wherein all four point electrodes are located within the surface of the catheter forming no more than half of the circumference of the catheter when viewed from its distal end, such that all four point electrodes are capable of simultaneous contact with the surface of the heart during the mapping activity,
sensing signals in heart tissue using the first and second bipolar pairs of electrodes to determine the general location of the cardiac arrhythmia focus within the heart, and
determining the precise location of the cardiac arrhythmia focus using a unipole electrode secured to the catheter body.